var arr = ['短跑','接力','短跑','拔河','跳绳','接力','拔河','跳远'];
function unique(arr) {
    var newArr = [];
    for(var i =0;i<arr.length; i++){
        if(newArr.indexOf(arr[i])===-1){
            newArr.push(arr[i]);
        }
    }
    return newArr;
}
console.log(unique(arr));